The field of this invention relates to measurement of the concentration of the hormone pregnanediol in women's urine. In urine, this hormone occurs in the form of pregnanediol glucuronide (PG) and is detected in that form. The amount of PG in a woman's urine rises rapidly at the time of ovulation, and declines rapidly at the time of menstruation. However, if conception has occurred, the PG level remains high. Therefore, measurement of pregnanediol levels in urine is a potential usable procedure for either preventing or diagnosing pregnancy.
Although ovulation may be detected by characteristic in basal body temperature or in physical properties of cervical mucus, these methods are subject to variability from body functions unrelated to ovarian function and therefore not sufficiently reliable for detecting ovulation in many women.
Although pregnanediol is the major urinary product of progesterone, pregnanediol assays have not been widely utilized for assessment of luteal function. There are basically two reasons for this. First, earlier methods have required the collection of 24-hour urine specimens, an unreasonable request for even highly motivated patients when, to be most useful, collections should be made daily for at least 10 days during the middle of the menstrual cycle. Second, the assay procedure has been laborious, requiring usually two days for completion, and is subject to errors from several sources; the necessity for enzymatic or acid hydrolysis of the glucuronide moiety for colorimetry or gas chromatography is the most difficult and variable aspect of the assay.
It has been demonstrated that measurements of PG levels in overnight urine specimens correspond closely with 24-hour specimens. See Judge, et al, Steroids 31: 175-187 (1978). The reported tests were conducted on a laboratory basis by a gas chromatographic method.
Samarajeewa, et al have published a method for preparing antiserum specific for PG. J. Steroid Biochem. 11: 1165-1171 (1979). Pregnanediol in its free acid form was joined covalently to bovine serum albumin, and the antisera was prepared in rabbits. A calibration curve was prepared with radio-labelled PG, as part of the development of direct radioimmunoassay procedure for PG in women's urine. Specificity was established by showing that other steroids present in urine did not cross-react.
The antiserum prepared as described by Samarajeewa, et al, was used by Collins et al in radioimmunoassay procedure for measuring PG in overnight and 24-hour urine samples. Acta Endocrinologica 90: 336-348 (1979). The results confirmed the correlation previously observed by Judge et al. In the reported assay procedure, radio-labelled PG was employed as the test reagent for competing with the urine PG in binding to the antibodies of the immune serum. Thus, an expensive and relatively unstable reagent, pregnanediol glucuronide was required both for preparing the antiserum and as a radio-labelled test reagent, and the radioimmunoassay was carried out on a laboratory basis requiring special equipment. Heretofore, no one has provided the ovulation detection art with a simple, inexpensive and accurate procedure for determining levels of PG in urine which can be employed by women on a home-use basis.